Configbuilder: refactor & clean up code

Description

Some of the code requires refactoring and cleaning up to improve readability and maintainability. Additionally, some screens, e.g. FinalInfraDetails, load slowly and with some visual glitches.

Example

One area for improvement is the handling of button presses.

• Capturing button presses isn’t consistent; sometimes we are using the @on decorator, other times we are defining a special on_button_pressed method. This could be standardised.
• Some button press logic is defined globally in the ConfigsCreateApp class, others are defined within the screens they appear on. This makes sense for the back button logic which has the global effect of running self.pop_screen(), but might not be the best place to put other event handlers, and can make it difficult to work out the flow of the app.
• When next buttons are pushed, many screens run similar code to iterate through the text fields on the screen and add the data to the Pydantic model. This results in some code duplication. Could we clean this up and create a single method that all screens could use?

Tasks

• Identify places in the app code that could be refactored, consolidated, or otherwise re-written to improve readability and maintainability.
  • The major places for refactoring will be in the utils.py module and any code related to updating and validating the Pydantic model.
• (Optional) For large refactors, create a sub-issue to track the work
• Update code accordingly and test

We'll be working on this issue at the 2026 hackathon Sydney hub

Start in utils.py and ConfigsCreateApp, then trace the screen code around FinalInfraDetails and the Pydantic model updates and validation. Review the duplicated button handlers and next-button field processing first; done means the refactoring is implemented and the affected code is tested without the reported slow loading or visual glitches.